Un reachable USB dongle
I Have sentinal pro dongle for 800Xa system
The USB is un available in the available machine ID in license entry
w euse Server windows 2008 32 Dell power edge R710
Voted best answer
Please check is your computer is detected the sentinal pro dongle, you can find this in Device manager-USB serial bus controllers , if it is detected as know device then only you get machine id in license entry.
If your system not detecting setinal pro -
-Ttry with other usb port
-Check setinal pro in any computer then u came to know where is the problem.
you can load the driver from the licence entry console, tools-load setinal pro driver